Masonry Magazine August 1992 Page. 28
Design Example #2: Steel Pier with 4 Inch Panel Noise Barrier Wall
Type S portland cement/lime mortar, f'm 3000 psi, Em 2.8 x 106 psi. Wall dimensions shown in Fig. 4. Running bond, full bedding, spacing of piers shall be 15 ft. Ladder type joint reinforcement: fy 80 ksi, E 29 × 106 psi, n 10.4. Pier I-beam: Grade 50 W Section, E, 29 x 106 psi. Loads: wind 15 psf, panel weight 25 psf, seismic 40 psf.
# Step 1
Based on acoustical considerations, the wall height shall be 16 ft minimum.
# Step 2
Critical load combinations result in the following design values:
a) For the panel span between piers (per foot of wall): Mpx (1/8)(W)(L)2 (1/8) (25 psf)(15 ft) = 703 ft-lb. Mpy = (1/10)(h/L)(Mpx)= (1/10)(16 ft/15 ft) (703 ft-lb) 75 ft-lb. Vpx (0.5)(W)(L) = (0.5)(25 psf)(15 ft) = 188 lb.
b) For the panel span between caissons, assume the panel is supported along its entire base by the ground.
c) For an interior steel pier: M (0.5)(2)(Vpx)(h)2= (0.5)(2)(188 lb/ft)(16 ft)2 = 48,130 ft-lb. M1.3M 1.3 (48,130 ft-lb) 62,570 ft-lb. V= (2)(Vpx)(h)(2)(188 lb/ft)(16 ft) = 6016 lb. V1.3V 1.3 (6016 lb) 7820 lb.
# Step 3
Calculate required reinforcement for the panel for the design moment Mpx. Assume the distance from the extreme compression face to the joint reinforcement is 3 inches. As req'd = Mpx / Fajd = 703 ft-lb (12 in./ft) / (4/3) (30 ksi)(0.9)(3 in.) = 0.078 in.2
Try ladder type W1.7 wire reinforcement in every course, with a 2.25 in. high brick. Therefore, A, 0.077 in.2 per foot of panel (Table 4). pn = An (0.077 in.2)(10.4) / bd (12 in.)(3 in.) = 0.0222
# FIG. 4
CAISSON BEYOND
SEALANT AND BACKER
ROD, TYP
LADDER TYPE
JOINT REINFORCEMENT
AS REQUIRED
19-5/8 IN.
CLIP ANGLE WITH
BEARING PAD, TYP.
3 IN.
16-3/8 IN.
3-5/8 IN.
16-3/8 IN.
BRICK SURROUND
STEEL PIER AS REQUIRED
Noise Barrier Wall Design Example #2
Steel Pier With 4 Inch Panel